Mapping World War One

Guest blog by Ian Robinson at OS

Following my appearance on the Remembrance Sunday edition of BBC Countryfile describing the role OS played during WWI, I was contacted by 135 Geographic Squadron Royal Engineers and invited to attend a battlefield study in Belgium.


Based at Ewell in Surrey, 135 Squadron is the reservist squadron of 42 Engineer Regiment. Their role is the acquisition, analysis, management and distribution of geographic information and data in a variety of formats to the army. It is staffed by reservists expected to fulfil the same role as their regular army counterparts; indeed several members of the squadron served in recent operations in Iraq and Afghanistan.

The purpose of the study was to look at the battlefields of 1915 where the Royal Engineers (the Sappers) and its surveyors – many from OS – had prominence, in particular the battle of Neuve Chapelle. The study investigated the types of terrain encountered the by the surveyors around the Ypres salient and the problems of running theodolite and chain traverses in such flat country, under observation of the enemy occupying the higher ground.

Using equipment drawn from the OS archive store, my part was to demonstrate the Troughton and Simms 7½ inch theodolite used at the time for measuring horizontal and vertical angles and its use providing a control network up to the front line through traverse and triangulation schemes. I showed how the plane table was used by surveyors to carry out detail surveys, commonly at 1:5,000 scale and the drills surveyors carried out to measure distances with heavy measuring chains.


The battle of Neuve Chapelle took place during the 10-12 March 1915 and was meant to demonstrate to the senior French forces that the British Army could attack successfully by breaking through German lines and capturing their high ground (described as a ‘ridge’ but was little more than two metres higher than the surrounding land!).

It was “a first” for several reasons; it was the first offence by the British army after months of defence, the first use of reservists and Indian troops (until then both considered inferior by the regular soldiers) and the first battle where aerial photography was used, not only to provide intelligence on enemy positions and strengths but also to update maps and plot trench plans to depict this. OS draftsmen were moved to France to update and produce maps from the photographs and produce photographic mosaics, which they annotated with English names (e.g. Ploegsteert became Plug Street) and enhanced features, such as trench systems, to make it easier for the planners to interpret the imagery.

Surveyors fixed precise coordinated points for artillery batteries to fire from and through intersection methods were able to fix prominent targets behind enemy lines to make that fire more effective and efficient.

After initial success the attack floundered due to communication failures and a strong counter attack by the Germans. Both sides suffered 12,000 casualties. In this respect it is the first of many such attacks mounted throughout the war, where gains were negligible and the cost in lives high.

I was able to visit two cemeteries in Ypres where OS staff members are buried, F G Harvey and W J Barnes and attended the last post ceremony at the Menin gate memorial, where members of the Squadron laid a wreath. The memorial is for 54,000 British and Commonwealth troops killed on the salient and have no known grave, including two OS staff members, J Donnellan and A E Smith.

You can find out more about our history on our website.



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6 Responses

  1. Adam

    Hello Gemma and Ian.

    Could you comment on what kind of time frame it may take to complete a plane table resection for a battery position? I realize that it would depend on a lot of factors including the availability of known points, but I’m looking to establish a baseline on how long it would take an experienced surveyor to do the task.

    1. Jocelyn

      Thanks for your question. This has been passed on to Ian and he will get back to you as soon as he can. Many thanks, Jocelyn

    2. Jocelyn

      Hi Adam. Ian has spoken with a former colleague to compare notes on plane tabling. Based on their experience, there is a best and worst scenario. The best is single set up in the actual gun position and to do a simple resection using several known features identifiable on the map. This would take an experienced surveyor 20 minutes tops. The worst case involves running a traverse (measuring angles and distances) from a known point into the gun position. Depending on the distance to measure and the terrain you are working over, that could easily take 3 – 4 hours. Hope this helps, Jocelyn

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